A typical fire suppression device comprises a cannister of pressurized fire suppression material and a valve. The fire suppression material in the cannister may include a propellant, if necessary, to discharge the fire suppression material. The valve has an outlet port through which suppression material from the cannister is discharged. The valve typically has a valve member or piston which moves inside a central chamber between a closed position, in which the suppression material is prevented from reaching the outlet port, and an open position, in which the suppression material is released. The piston is normally latched in the closed position to resist a pressure force from the pressurized suppression material. The latch may be selectively released, allowing the pressure on the piston to displace it, opening the discharge port which it had blocked.
A substantial concern with such fire suppression devices is the unintended discharge of fire suppression material. It will be appreciated that such devices are designed for rapid release of pressurized suppression material. Accordingly, fire suppression devices employ a variety of highly responsive trigger mechanisms, such as manual pulls or sensitive solenoid actuators. Regardless of the mechanism, a danger exists of accidental or unintended triggering of the device which releases the fire suppression material. Accidental discharges waste suppression material and require cleanup and recharging of the devices.
More significantly, personal injury or death may result when a fire suppression device accidentally discharges in the vicinity of personnel. In certain applications, such as use inside the Bradley fighting vehicle, fire suppression devices are installed in fixtures attached to the vehicle. The fixtures incorporate a hose for directing discharge of suppression material. Accordingly, it is important to prevent unintended discharge during transport and installation, since such discharge may cause injury or death to the handler. The relatively compact interior of the Bradley fighting vehicle increases the chances of such discharge striking personnel.
Certain fire suppression devices incorporate safeties which do not adequately protect against accidental discharge of suppression material. The safeties used in these devices focus on preventing a trigger mechanism from operating. For example, some devices employ a safety pin which locks a mechanical pull trigger in position to prevent operation. Safety pins, however, do not prevent unintended actuation of non-mechanical type trigger mechanisms, such as solenoid-actuated mechanisms. Furthermore, the mechanical safety does not protect against discharge due to internal failure of the valve. In addition, the pin must first be removed before the trigger mechanism can operate to release suppression material. Accordingly, such safeties are not suitable for applications requiring instantaneous discharge, as in military applications where advanced sensors can trigger highly responsive extinguishers to provide important life-saving functionality. Furthermore, most conventional safeties require manual manipulation by the user to set.